As a result of continued improvement in the performance of computers and the rapid growth of broadband infrastructure, various machine translation devices and services for translating a first language (original text) to a second language (translated text) have become popular. General machine translation has multiple translation candidates of the second language for a word or a clause in the first language. In such a system, a suitable translation for an input first language should be selected in terms of accuracy and fluency. A statistically-based translation system can be used to select a suitable translation; however, a massive bilingual corpus is necessary for such a system. To avoid this, cooccurrence words of the first and second languages can be used in considering accuracy.